Basic search in ES with the elastic/go-elasticsearch client

esClient.go

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"strings"

	"github.com/elastic/go-elasticsearch"
)

// Look for the movie in elasticSearch
func esSearch(query string) {
	res, err := esConn.Search(
		// esConn.Search.WithIndex("INDEX"), // you can especify an index
		esConn.Search.WithBody(strings.NewReader(query)),
	)
	if err != nil {
		log.Fatalf("ERROR: %s", err)
	}
	defer res.Body.Close()

	if res.IsError() {
		log.Println("Error in the elasticserch query: ", err)
	}

	var response map[string]interface{}

	if err := json.NewDecoder(res.Body).Decode(&response); err != nil {
		log.Printf("Error parsing the response body: %s", err)
	}

	for _, hit := range response["hits"].(map[string]interface{})["hits"].([]interface{}) {
		log.Printf("Result: %s", hit.(map[string]interface{})["_source"])
	}
}

var esConn *elasticsearch.Client

// Connect to elasticsearch
func esConnect() {
	log.Println("Connecting to Elastich Search")
	addr := fmt.Sprintf("http://%s:%s", os.Getenv("ES_HOST"), os.Getenv("ES_PORT"))
	cfg := elasticsearch.Config{
		Addresses: []string{
			addr,
		},
	}
	es, err := elasticsearch.NewClient(cfg)
	if err != nil {
		log.Fatal("Unable to connect to ES")
	}
	esConn = es
	return
}

// Check if env variables are setted
func preflightCheck() {
	if _, ok := os.LookupEnv("ES_HOST"); !ok {
		log.Fatal("No elasticsearch host configured")
	}
	if _, ok := os.LookupEnv("ES_PORT"); !ok {
		log.Fatal("No  elasticsearch port configured")
	}
}

func main() {
	preflightCheck()

	// Search for every document
	query := `{"query" : { "match_all" : {} }}`

	// Connect to ES and save the conn into the global variable
	esConnect()

	// Make the query to ES
	esSearch(query)
}